admin_main.php

<?php
class AdminMain extends DatabaseManagerController {
    public function index(){
        
    }
}
?>

/** According o docs.blesta.com/display/dev/Plugin+Actions this should automatically render the proper view without setting it

database_manager_controller.php

<?php
class DatabaseManagerController extends AppController {
	public function preAction(){
		parent::preAction();

		// Require login
		// $this->requireLogin();

		$this->uses(array("Backup"));
	
		$this->view->view = "default";
		$this->orig_structure_view = $this->structure->view;
		$this->structure->view = "default";
	}
}
?>

database_manager_plugin.php

<?php
class DatabaseManagerPlugin extends Plugin {
    // Provide a widget on staff's view of a client
    public function getActions() {
        return array(
            array(
                "action" => "widget_staff_client",
                "uri" => "plugin/database_manager/admin_main/index/",
                "name" => "Database Management",
                "options" => null
            )
        );
    }
    
	public function __construct(){
		$this->loadConfig(dirname(__FILE__) . DS . "config.json");
	}
}
?>